Orca (Orcinus orca)

Description: Orcas, also known as killer whales, are the largest species in the dolphin family. The males can grow up to 10 m long and have a dorsal fin that’s 2 m tall. They are pure black with a white underside and a white patch on each side of their face. They can also have a faint white saddle behind the dorsal fin. Orcas are highly intelligent and social animals. They travel in pods, and each group of orcas has distinct behaviors and vocalizations that create unique cultures. They hunt cooperatively in groups like a wolf pack, and can take down prey as large as great white sharks and whale calves, making them one of the top predators of the ocean. Orcas can be broken into three ecotypes, or subgroups, based on their diet, behavior, and appearance. Resident orcas have rounded dorsal fins and have large pods. Transient orcas have more straight dorsal fins and more distinct white saddle patches. Offshore orcas have rounded dorsal fins and live in large pods like Resident orcas, but are much smaller than both Resident and Transient ecotypes.

Habitat: Orcas are found around the world, but each ecotype has a territory that they inhabit. In the Pacific Northwest, the Resident pods range from the Puget Sound to southeastern Alaska, staying close to shore. The Transient ecotype ranges from southeast Alaska to southern California and can been seen nearshore or several miles out. Offshore orcas are found in the open ocean all around the Pacific. All three ecotypes can occasionally be seen on the Oregon Coast.

Diet: The diet of orcas is dependent on what ecotype they belong to. The Resident orcas are known for eating fish, those in the Puget Sounds eat exclusively chinook salmon. Transient orcas tend to eat more marine mammals like seals, sea lions, and whale calves. The least is known about Offshore orcas, but they are believed to primarily eat big fish, including sharks.

Tide Pool Tidbits:

• Orcas have a matriarchal social structure.

• Females have a longer life span than males, and are one of the few species, besides humans, that go through menopause. Elderly female orcas continue to assist the pod by helping her daughters rear young.

• Although the worldwide population of orcas is stable, the Southern Resident orcas are listed as endangered due to decreased reproductive rates and increased infant mortality in recent years. The chinook salmon population has decreased in the Puget Sound and with less food for the Southern Resident orcas, their population is decreasing as well.

References: NOAA, ODFW, Port Townsend Marine Science Center